Packet-switched wireless communication for link budget limited wireless devices

ABSTRACT

This disclosure relates to techniques for a link budget limited UE to improve communications performance with a cellular network. The UE may perform signal to interference noise ratio (SINR) measurements and use these measurements to adjust a received signal power value that is provided to the cellular network as a received signal power measurement. The UE may generate the received signal power value based at least in part on the SINR measurement in order to reduce the likelihood of handover when the UE has good SINR but poor received signal power. The UE may also provide preferred configuration information to the base station which enhances the performance of the UE when link budget limited. The configuration information may specify one or more parameter values designed to provide improved performance for a link budget limited device.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.15/153,676 titled “Packet-Switched Wireless Communication for LinkBudget Limited Wireless Devices,” filed May 12, 2016, which claimsbenefit of priority of U.S. Provisional Patent Application Ser. No.62/163,340 titled “Packet-Switched Wireless Communication for LinkBudget Limited Wireless Devices,” filed May 18, 2015, and which are bothhereby incorporated by reference as though fully and completely setforth herein.

The claims in the instant application are different than those of theparent application or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication or any predecessor application in relation to the instantapplication. The Examiner is therefore advised that any such previousdisclaimer and the cited references that it was made to avoid, may needto be revisited. Further, any disclaimer made in the instant applicationshould not be read into or against the parent application or otherrelated applications.

FIELD

The present application relates to wireless devices, and moreparticularly to an apparatus, system, and method for providing improvedpacket-switched communication procedures for link budget limitedwireless devices.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage.Additionally, there exist numerous different wireless communicationtechnologies and standards. Some examples of wireless communicationtechnologies include GSM, UMTS (associated with, for example, WCDMA orTD-SCDMA air interfaces), LTE, LTE Advanced (LTE-A), HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN orWi-Fi), IEEE 802.16 (WiMAX), Bluetooth, and others.

Wireless communication can be useful for a wide breadth of deviceclasses, ranging from relatively simple (e.g., potentially inexpensive)devices, which may have limited capabilities, to relatively complex(e.g., potentially more expensive) devices, which may have greatercapabilities. Such devices may have different characteristics withrespect to processing, memory, battery, antenna (power/range,directionality), and/or other capabilities. Devices that exhibitrelatively limited reception and/or transmission capabilities (due todevice design, device size, battery size, current transmission mediumconditions, and/or other factors) may be referred to in some instancesas “link budget limited” devices.

SUMMARY

Embodiments are presented herein of methods for providing improvedpacket-switched wireless communication performance for link budgetlimited devices, and of devices (e.g., wireless devices (UEs), basestations) configured to implement the methods. For example, embodimentspresented herein may provide improved LTE or LTE-Advanced performancefor link budget limited devices. Some embodiments may relate to a userequipment (UE) that comprises at least one antenna, at least one radio,and a processing element, and which is configured to perform a subset orall of the operations described herein.

According to techniques described herein, the UE (which may be linkbudget limited) may connect to a base station in a first cell in acellular network and may perform a measurement of signal to interferencenoise ratio (SINR) of communications received by the UE in the firstcell (e.g., may perform an SINR measurement). The UE may then generate areceived signal power value based at least in part on the SINRmeasurement and communicate this generated received signal power valueto the base station as a received signal power measurement. The UE maygenerate the received signal power value based at least in part on theSINR measurement in order to reduce the likelihood of handover when theUE has good SINR but poor received signal power. The generated receivedsignal power value may be used by the base station in determining when ahandover of the UE should occur from the first cell to a second cell.

In some embodiments, the UE may perform an actual measurement ofreceived signal power (e.g., an RSRP and/or RSRQ measurement) from thebase station to produce a first received signal power value. The UE maythen adjust the first received signal power value based on the SINRmeasurement to produce a second different received signal power value,for example by adding an offset that corresponds to an amount of theSINR measurement. The UE may then report this second received signalpower value to the network as the received signal power measurement. Inanother embodiment, the UE may comprise a memory which stores a datastructure mapping SINR measurements to received signal power values.Here, the UE may generate the received signal power value by mapping anactual SINR measurement to a corresponding (artificially generated)received signal power value using the data structure.

The UE may be configured to communicate with the cellular networkaccording to a first cellular radio access technology (RAT), wherein thefirst RAT specifies that the UE report a received signal powermeasurement to the cellular network for use in determining whether tohandover the UE from the first cell to a second cell. However, for alink budget limited device, a report of measured received signal powermay not provide an accurate indication of when a handover should occur.Thus instead the UE may perform a different type of measurement, such asSINR, and may generate/report a received signal power value that isbased at least in part on this SINR measurement.

According to further techniques described herein, the UE (which may belink budget limited) may wirelessly connect to a base station in a firstcell in a cellular network and provide configuration information to thebase station. The configuration information may specify one or moreparameter values designed to provide improved performance for a linkbudget limited device, wherein the one or more parameter values areusable to configure the cellular network and/or the UE. The cellularnetwork may receive this configuration information and may determine toconfigure itself and/or the UE accordingly. The UE may then receive acommunication from the base station specifying usage of the one or moreparameter values, and the UE may configure itself according to theseparameter values in response. After being configured, the UE operateswith improved performance when link budget limited.

The configuration information may comprise a plurality of parametervalues. Alternatively, the configuration information may comprise anindex value that is usable by the cellular network to identify a set ofparameter values pre-stored in the cellular network. The index value maybe a first index value of a plurality of possible index values, whereineach of the plurality of possible index values specifies or maps to arespective set of parameter values that are usable to configure the UE.

In some embodiments, the UE is configured to communicate according to afirst radio access technology (RAT), wherein the RAT conforms to a RATstandard. The one or more parameters may specify one or more differentvalues for parameters which do not conform to the RAT standard. Forexample, the RAT standard may specify a first period of time for the UEto perform a first action, and the one or more parameter values maycomprise at least one timer value which increases the first period oftime to a larger second period of time in which the UE is allowed toperform the first action.

The following are various examples of timers which may be modified fromthe prescribed values specified in the standard. For example, varioustimer values may be increased (allowing for an increased amount of time)relative to the RAT standard, or may be reduced (allowing for adecreased amount of time) relative to the RAT standard. The one or moreparameter values may comprise one or more of the following: 1) ahandover failure timer value, which provides an increased amount of timeafter which a handover failure is deemed to have occurred, wherein thehandover failure timer value is larger than that specified in the RATstandard; 2) a time-to-trigger timer value, which provides an increasedamount of time for measurement reporting, wherein the time-to-triggertimer value is larger than that specified in the RAT standard; 3) ahandover preparation timer value, which provides an increased amount oftime for handover preparation, wherein the handover preparation timervalue is larger than that specified in the RAT standard; 4) a radio linkfailure timer value, which provides an increased amount of time before aradio link failure procedure is invoked, wherein the radio link failuretimer value is larger than that specified in the RAT standard; 5) apacket discard timer value, which provides an increased amount of timebefore a packet is discarded from a buffer, wherein the packet discardtimer value is larger than that specified in the RAT standard; 6) afirst radio link failure timer value, which provides an increased amountof time before triggering a radio link failure procedure, wherein thefirst radio link failure timer value is larger than that specified inthe RAT standard; and 7) a second radio link failure timer value, whichprovides a reduced amount of time before stopping a radio link failureprocedure, wherein the second radio link failure timer value is smallerthan that specified in the RAT standard.

The one or more parameter values may also specify other changes from theRAT standard. For example, the one or more parameter values maycomprise: 1) a first value that specifies an increased maximum signalstrength measurement of a neighboring cell relative to a threshold forhandover management, wherein the first value is different than thatspecified in the RAT standard; 2) a first value that specifies anincreased maximum number of radio link control retransmissions to avoidradio link failure, wherein the first value is different than thatspecified in the RAT standard; 3) a first value that specifies a lowerperiodicity of channel quality reporting than that specified in the RATstandard; 4) a first value that specifies a reduced number of maximumscheduling request attempts than that specified in the RAT standard; 5)a first value that specifies an increased number of random accesschannel attempts than that specified in the RAT standard; 6) a firstvalue that specifies an increased amount of delay in performance of anout of service procedure than that specified in the RAT standard; and 7)a handover event value that specifies a signal strength measurement of aneighboring cell relative to a threshold for handover management.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, tablet computers, wearable computing devices, portablemedia players, and any of various other computing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings, in which:

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments;

FIG. 2 illustrates a base station (BS) in communication with a userequipment (UE) device, according to some embodiments;

FIG. 3 illustrates an exemplary block diagram of a UE, according to someembodiments;

FIG. 4 illustrates an exemplary block diagram of a BS, according to someembodiments;

FIG. 5 is a flowchart diagram illustrating a method to perform handoverand cell reselection in a cellular network adapted for a link budgetlimited UE, according to some embodiments;

FIG. 6 is a flowchart diagram illustrating a method for a link budgetlimited UE to modify communication parameters in a cellular network,according to some embodiments; and

FIG. 7 illustrates operation of various timers for handover andreestablishment, according to some embodiments.

While the features described herein may be susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION

Acronyms The following acronyms are used in the present disclosure.3GPP: Third Generation Partnership Project 3GPP2: Third GenerationPartnership Project 2 UMTS: Universal Mobile Telecommunication SystemEUTRA: Evolved UMTS Terrestrial Radio Access GSM: Global System forMobile Communications LTE: Long Term Evolution PLMN: Public Land MobileNetwork CQI: Channel Quality Indicator QCI: Quality of Service ClassIdentifier GBR: Guaranteed Bit Rate RAT: Radio Access Technology RRC:Radio Resource Control RSRP: Reference Signal Received Power RSRQ:Reference Signal Received Quality RX: Receive RLC: Radio Link ControlRLF: Radio Link Failure TX: Transmit UE: User Equipment UMTS: UniversalMobile Telecommunications System

Terms

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g., smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless cellular telephone system or cellular radio system.

Processing Element—refers to various elements or combinations ofelements. Processing elements include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors.

Link Budget Limited—includes the full breadth of its ordinary meaning,and at least includes a characteristic of a wireless device (a UE) whichexhibits limited communication capabilities, or limited power, relativeto a device that is not link budget limited, or relative to devices forwhich a radio access technology (RAT) standard has been developed. A UEthat is link budget limited may experience relatively limited receptionand/or transmission capabilities, which may be due to one or morefactors such as device design, device size, battery size, antenna sizeor design, transmit power, receive power, current transmission mediumconditions, and/or other factors. Such devices may be referred to hereinas “link budget limited” (or “link budget constrained”) devices. Adevice may be inherently link budget limited due to its size, batterypower, and/or transmit/receive power. For example, a smart watch that iscommunicating over LTE or LTE-A with a base station may be inherentlylink budget limited due to its reduced transmit/receive power and/orreduced antenna. Alternatively, a device may not be inherently linkbudget limited, e.g., may have sufficient size, battery power, and/ortransmit/receive power for normal communications over LTE or LTE-A, butmay be temporarily link budget limited due to current communicationconditions, e.g., a smart phone being at the edge of a cell, etc. It isnoted that the term “link budget limited” includes or encompasses powerlimitations, and thus a power limited device may be considered a linkbudget limited device.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually,” where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments. It is noted that the system ofFIG. 1 is merely one example of a possible system, and embodiments maybe implemented in any of various systems, as desired.

As shown, the exemplary wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore user devices 106A, 106B, etc., through 106N. Each of the userdevices may be referred to herein as a “user equipment” (UE). Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station 102A may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UEs 106A through 106N. The base station 102A may also be equipped tocommunicate with a network 100 (e.g., a core network of a cellularservice provider, a telecommunication network such as a public switchedtelephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102A may facilitate communicationbetween the user devices (UEs) and/or between the UEs and the network100.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102A and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as GSM,UMTS (WCDMA, TD-SCDMA), LTE, LTE-Advanced (LTE-A), HSPA, 3GPP2 CDMA2000(e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106A-N and similar devices over a wide geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs 106A-Nas illustrated in FIG. 1, each UE 106 may also possibly come withincommunication range of, and be capable of receiving signals from, one ormore other cells (which might be provided by base stations 102B-N and/orany other base stations), which may be referred to as “neighboringcells.” Such cells may also be capable of facilitating communicationbetween user devices and/or between user devices and the network 100,according to the same wireless communication technology as base station102A and/or any of various other possible wireless communicationtechnologies. Such cells may include “macro” cells, “micro” cells,“pico” cells, and/or cells which provide any of various othergranularities of service area size. For example, base stations 102A-Billustrated in FIG. 1 might be macro cells, while base station 102Nmight be a micro cell. Other configurations are also possible.

Note that a UE 106 may be capable of communicating using multiplewireless communication standards. For example, a UE 106 may beconfigured to communicate using a wireless networking (e.g., Wi-Fi)and/or peer-to-peer wireless communication protocol (e.g., BT, Wi-Fipeer-to-peer, etc.) in addition to at least one cellular communicationprotocol (e.g., GSM, UMTS (WCDMA, TD-SCDMA), LTE, LTE-A, HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc.). The UE 106 may alsoor alternatively be configured to communicate using one or more globalnavigational satellite systems (GNSS, e.g., GPS or GLONASS), one or moremobile television broadcasting standards (e.g., ATSC-M/H or DVB-H),and/or any other wireless communication protocol, if desired. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106Athrough 106N) in communication with a base station 102 (e.g., one of thebase stations 102A through 102N), according to some embodiments. The UE106 may be a device with cellular communication capability such as amobile phone, a hand-held device, a wearable device, a computer or atablet, or virtually any type of wireless device.

The UE 106 may include a processor that is configured to execute programinstructions stored in memory. The UE 106 may perform any of the methodembodiments described herein by executing such stored instructions.Alternatively, or in addition, the UE 106 may include a programmablehardware element such as an FPGA (field-programmable gate array) that isconfigured to perform any of the method embodiments described herein, orany portion of any of the method embodiments described herein.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols or technologies. In someembodiments, the UE 106 might be configured to communicate using eitherof CDMA2000 (1×RTT/1×EV-DO/HRPD/eHRPD) or LTE using a single sharedradio and/or GSM or LTE using the single shared radio. The shared radiomay couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. In general, aradio may include any combination of a baseband processor, analog RFsignal processing circuitry (e.g., including filters, mixers,oscillators, amplifiers, etc.), or digital processing circuitry (e.g.,for digital modulation as well as other digital processing). Similarly,the radio may implement one or more receive and transmit chains usingthe aforementioned hardware. For example, the UE 106 may share one ormore parts of a receive and/or transmit chain between multiple wirelesscommunication technologies, such as those discussed above.

In some embodiments, the UE 106 may include separate (and possiblymultiple) transmit and/or receive chains (e.g., including separate RFand/or digital radio components) for each wireless communicationprotocol with which it is configured to communicate. As a furtherpossibility, the UE 106 may include one or more radios which are sharedbetween multiple wireless communication protocols, and one or moreradios which are used exclusively by a single wireless communicationprotocol. For example, the UE 106 might include a shared radio forcommunicating using either of LTE or 1×RTT (or LTE or GSM), and separateradios for communicating using each of Wi-Fi and Bluetooth. Otherconfigurations are also possible.

FIG. 3—Exemplary Block Diagram of a UE

FIG. 3 illustrates an exemplary block diagram of a UE 106, according tosome embodiments. As shown, the UE 106 may include a system on chip(SOC) 300, which may include portions for various purposes. For example,as shown, the SOC 300 may include processor(s) 302 which may executeprogram instructions for the UE 106 and display circuitry 304 which mayperform graphics processing and provide display signals to the display360. The processor(s) 302 may also be coupled to memory management unit(MMU) 340, which may be configured to receive addresses from theprocessor(s) 302 and translate those addresses to locations in memory(e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310)and/or to other circuits or devices, such as the display circuitry 304,wireless communication circuitry 330, connector I/F 320, and/or display360. The MMU 340 may be configured to perform memory protection and pagetable translation or set up. In some embodiments, the MMU 340 may beincluded as a portion of the processor(s) 302.

As shown, the SOC 300 may be coupled to various other circuits of the UE106. For example, the UE 106 may include various types of memory (e.g.,including NAND flash 310), a connector interface 320 (e.g., for couplingto a computer system, dock, charging station, etc.), the display 360,and wireless communication circuitry 330 (e.g., for LTE, Wi-Fi, GPS,etc.).

The UE device 106 may include at least one antenna (and possiblymultiple antennas, e.g., for MIMO and/or for implementing differentwireless communication technologies, among various possibilities), forperforming wireless communication with base stations and/or otherdevices. For example, the UE device 106 may use antenna(s) 335 toperform the wireless communication. As noted above, the UE 106 may beconfigured to communicate wirelessly using multiple wirelesscommunication technologies in some embodiments.

As described further subsequently herein, the UE 106 may includehardware and software components for implementing features and methodsdescribed herein, such as those described herein with reference to,inter alia, FIG. 5. The processor 302 of the UE device 106 may beconfigured to implement part or all of the methods described herein,e.g., by executing program instructions stored on a memory medium (e.g.,a non-transitory computer-readable memory medium). In other embodiments,processor 302 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit). Alternatively (or in addition), theprocessor 302 of the UE device 106, in conjunction with one or more ofthe other components 300, 304, 306, 310, 320, 330, 335, 340, 350, 360may be configured to implement part or all of the features describedherein, such as the features described herein with reference to, interalia, FIGS. 5 and/or 6.

FIG. 4—Exemplary Block Diagram of a Base Station

FIG. 4 illustrates an exemplary block diagram of a base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The antenna(s) 434 may be configured to operate as awireless transceiver and may be further configured to communicate withUE devices 106 via radio 430. The antenna 434 communicates with theradio 430 via communication chain 432. Communication chain 432 may be areceive chain, a transmit chain or both. The radio 430 may be configuredto communicate via various wireless telecommunication standards,including, but not limited to, LTE, LTE-A, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly usingmultiple wireless communication standards. In some instances, the basestation 102 may include multiple radios, which may enable the basestation 102 to communicate according to multiple wireless communicationtechnologies. For example, as one possibility, the base station 102 mayinclude an LTE radio for performing communication according to LTE aswell as a Wi-Fi radio for performing communication according to Wi-Fi.In such a case, the base station 102 may be capable of operating as bothan LTE base station and a Wi-Fi access point. As another possibility,the base station 102 may include a multi-mode radio which is capable ofperforming communications according to any of multiple wirelesscommunication technologies (e.g., LTE and Wi-Fi).

The base station 102 may include hardware and software components forimplementing or supporting implementation of features described herein,such as those described herein with reference to, inter alia, FIGS. 5and 6. The processor 404 of the base station 102 may be configured toimplement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition), the processor 404 of the base station 102, inconjunction with one or more of the other components 430, 432, 434, 440,450, 460, and/or 470, may be configured to implement or supportimplementation of part or all of the features described herein, such asthe features described herein with reference to, inter alia, FIGS. 5 and6.

Handover and Cell Reselection

Handover (HO) and cell reselection may occur at the edge of a cell in acellular network. In some radio access technologies (RATs), ameasurement of “received signal power” is used by the cellular networkto determine whether to perform a handover. For example, the cellularnetwork may perform a handover when one or both of Reference SignalReceived Power/Reference Signal Received Quality (RSRP/RSRQ)measurements are below a certain threshold.

In the case of a link budget limited device, which may have reducedcapabilities as compared to other mobile communication devicesconforming to the RAT standard, including, for example, an antennadeficiency, the received signal power measurement might not be a goodindication of the quality of service, and hence might not serve as agood criterion in determining whether the link budget limited deviceshould undergo a handover. Thus, a link budget limited UE may benefitfrom a modification of the criteria used in handover and cellreselection, as discussed below in reference to FIG. 5. It is noted thatthe various operations described herein for link budget limited devicesalso applies to power limited UE devices, where the term “link budgetlimited” includes or encompasses power limited devices.

Some embodiments described herein relate to a link budget limited UEthat may use different (or modified) criteria than that specified in theRAT standard in determining handover and cell reselection At a celledge, the UE may most likely be interference limited, i.e., the signaland the interference may both be attenuated. In this case, even if themeasured received signal power (e.g., RSRP) is very low, another channelquality measurement, such as the Signal to Interference plus Noise Ratio(SINR) (the ratio of signal and interference) may still be good. TheRSRP may be low because it is a direct measurement of the receivedsignal alone, and the received signal power may be poor because the UEis at cell edge and the UE is otherwise link budget limited (e.g., itsantenna is relatively deficient). However, the SINR may indicate ausable or suitable wireless channel because both the signal strength andthe amount of interference are both similarly limited, and thus the SINRratio is fine. In this case, the UE may still be able to decode mostdownlink channels. Typically, in current systems, a cell reselection orhandover may be triggered if the RSRP is below −120 dBm. However, for anantenna deficient UE measuring an RSRP at that level, the measured SINRmay still be higher than 0 dB, indicating that the UE is still able tosuccessfully decode its DL channels.

FIG. 5—Flowchart

FIG. 5 is a flowchart diagram illustrating a method to perform handoverand cell reselection in a cellular network adapted for a link budgetlimited UE, according to some embodiments. While elements of the methodof FIG. 5 are described substantially with reference to the LTE wirelesscommunication technology, part or all of the method may be used inconjunction with other wireless communication technologies, as desired.

The method shown in FIG. 5 may be used in conjunction with any of thecomputer systems or devices shown in the above FIGS. 1-4, among otherdevices. In various embodiments, some of the elements of the schemeshown may be performed concurrently, in a different order than shown, ormay be omitted. Additional elements may also be performed as desired. Asshown, the scheme may operate as follows.

In 502, a link budget limited UE (e.g., UE 106) connects to a basestation (e.g., base station 102) in a cellular network. The cellularnetwork may conform to a radio access technology (RAT) standard, e.g., apacket-switched standard such as LTE or LTE-A. The cellular network mayprescribe that a certain metric, such as received signal power, bemeasured by the UE and provided to the cellular network, where thecellular network uses this measured received signal power in assessingwhether handover should be performed. However, as noted above, receivedsignal power may not be the best metric in determining whether handovershould occur for a link budget limited device.

In 504, the UE performs a received signal power measurement (e.g., RSRPand/or RSRQ), in which the UE measures the average power of resourceelements that carry cell-specific resource signals over the consideredmeasurement frequency bandwidth. In this way, the UE measures the signalstrength from a specific base station.

In 506, the UE performs a separate signal measurement, such as a signalto interference ratio measurement (e.g., a Signal to Interference plusNoise Ratio or SINR), in which the UE measures the power of the signalof interest divided by the sum of the interference power and thebackground noise power. The UE may perform other types of measurements,e.g., other ratio based measurements, which are more suitable todetermining the channel quality of a link budget limited device.

In 508, the UE uses the signal to interference ratio measurement toadjust the received signal power measurement. For example, the UE mayapply (add) an offset to the received signal power measurement (theRSRP/RSRQ), wherein the amount of the offset is based on the measuredSINR measurement in 506.

For example, the measurement of received signal power in 504 may producea first received signal power value, and the UE may adjust the firstreceived signal power value based on the SINR measurement in 506 toproduce a second different received signal power value. In adjusting thefirst received signal power value based on the SINR measurement, the UEmay be configured to add an offset to the first received signal powervalue to produce the second received signal power value. The amount ofthe offset may correspond, either in a linear or non-linear fashion, tothe amount of the SINR measurement. For example, when the SINRmeasurement is larger, the UE may be configured to report acorrespondingly larger second received signal power value as thereceived signal power measurement.

In 510 the UE may report the adjusted received signal power measurement(the second received signal power value) to the cellular network. Thisreported measurement is then used to determine whether handover shouldoccur. Thus, the received signal power value that the UE reports to thecellular network is not the actual value that was measured by the UE,but rather is a different value—a value that was produced by modifyingthe actual received signal power measurement.

Thus, in some embodiments, the cellular network may use SINR as a metricto trigger cell reselection or handover, instead of, or supplemental to,RSRP. The threshold value of SINR used by the UE for triggering cellreselection or handover may be the value (the amount of SINR) needed bythe UE to decode basic control channels like System Information Blocks(SIBs), the Physical Downlink Control Channel (PDCCH), etc. As describedabove, the UE may add an offset value to its RSRP/RSRQ measurementsbased on the SINR value that it observes or measures. For example, alink budget limited UE may measure the RSRP at −125 dBm and the SINR at6 dB. The RAT may be such that a UE that reports a RSRP measurementbelow −120 dBm triggers cell reselection or handover. However, becausethe SINR value indicates the UE is still able to successfully decode itsDL channels, the UE may add an offset value to its RSRP measurementbased on the SINR value, thus reporting a higher RSRP measurement valuethan what was actually measured. For example, the UE may report a RSRPmeasurement of −110 dBm, adding an offset of 10 dBm based on themeasured SINR value. The UE may then report the modified RSRPmeasurement (e.g., here, −110 dBm) to avoid triggering handover.

In some embodiments, even though the UE is required to report a“received signal power measurement” to the cellular network for thepurpose of handover management, the UE may not actually perform areceived signal power measurement in some instances. In theseembodiments, the UE may comprise a memory that stores a data structuremapping SINR measurements to received signal power values, and the UEgenerates a received signal power value by mapping an actual SINRmeasurement to a corresponding received signal power value using thedata structure. Thus, the received signal power value reported to thecellular network was not measured by the UE (and in fact no receivedsignal power measurement was performed in this time period), but rathera received signal power value is artificially determined by mapping anactual SINR measurement to the received signal power value. Thus here,the received signal power value is derived from the data structure, wasnot actually measured, and was not measured and modified as describedabove.

Call Flows for Link Budget Limited Devices

In some packet-switched wireless communication protocols, such as LTE, aUE may need to operate through different call flows in order toestablish a connection to the network and to maintain the connection.Different mechanisms may exist in the packet-switched wirelesscommunication protocol or RAT (e.g., LTE) specification to ensure thesecall flows operate correctly. Also, recovery mechanisms may exist incase of failure. However, these mechanisms may not be optimized for a UEthat is link budget limited. For example, timelines of such proceduresmay severely impact the operation of the battery. In addition,parameters of such procedures may not be optimized for link budgetlimited devices. Therefore, improvements in the field are desired.

FIG. 6—Flowchart

FIG. 6 is a flowchart diagram illustrating a method for a link budgetlimited UE to modify communication parameters in a cellular network,according to some embodiments. Note that while elements of the method ofFIG. 6 are described substantially with reference to the LTE wirelesscommunication technology, part or all of the method may be used inconjunction with other wireless communication technologies, as desired.

The method shown in FIG. 6 may be used in conjunction with any of thecomputer systems or devices shown in the above Figures, among otherdevices. In various embodiments, some of the elements of the schemeshown may be performed concurrently, in a different order than shown, ormay be omitted. Additional elements may also be performed as desired. Asshown, the scheme may operate as follows.

In 522, the link budget limited UE 106 communicates with a base station(for example, base station 102A) of a cellular network to establish aconnection with that base station for the provision of coverage in thecellular network.

In 524, the UE 106 indicates to the base station 102A that it is a linkbudget limited device. For example, the UE may provide a parameter valueduring radio resource control (RRC) messaging indicating that the UE islink budget limited. The cellular network may receive this value andadjust the manner in which the cellular network communicates with the UEaccordingly.

In 526, UE 106 provides preferred configuration parameters to the basestation 102A. The UE may provide these preferred configurationparameters to the cellular network during the RACH (Random AccessChannel) communication, in the RRC (radio resource control) signalingwith the base station (eNB). Alternatively, the UE may provide thesepreferred configuration parameters in a special handshaking protocol.

The preferred configuration parameters are desirable for configuring theUE 106 in accordance with the capabilities of UE 106 as a link budgetlimited device. The preferred configuration parameters may comprisevarious parameters that specific to a link budget limited device, andare usable to adapt communication between the UE and various basestations. These preferred communication parameters indicate, timervalues, criteria, and/or procedures associated with various link budgetlimited UE operations. The preferred communication parameters arediscussed further below with respect to each of these aspects of UE tobase station communication. It is noted that the UE indicating that itis link budget limited in 524 may occur in conjunction with (in the samecommunication) as the provision of preferred configuration parameters in526.

In some embodiments, the UE may provide the cellular network with anindex value that references or specifies a set of preferredconfiguration parameters, and not the parameters themselves. In theseembodiments, the cellular network may store a plurality of sets ofdifferent parameters, some for link budget limited UEs, some for normal(non-link budget limited) UEs, and some for different ranges or degreesof link budget constraints. The index value provided by the UE is usedby the cellular network to identify the desired set of preferredconfiguration parameters. For example, the cellular network may store adata structure which contains a mapping of these index values todifferent sets of pre-stored preferred configuration parameters.

In 528, UE 106 receives communication from the cellular network based onthe preferred configuration parameters. In other words, the cellularnetwork may receive the indication that the UE is link budget limitedand the preferred configuration parameters and decide to operate (andconfigure the UE to operate) as the UE has requested. In this instance,the cellular network issues commands to the UE to configure the UEaccording to all (or perhaps a subset of) the desired configurationparameters. The cellular network may also configure itself to operatebased on these preferred configuration parameters. In some instances,the respective base station (or the portion of the cellular network) maynot be programmed to be aware of this link budget limited signaling andmay ignore the information received in 524 and 526. In these instances,the UE is not configured based on its desired parameters.

Example Preferred Configuration Parameters

The following are example preferred configuration parameters that aremodified for a link budget limited device according to some embodiments.In most of the examples below, the UE provides a configuration parametervalue that is different than that specified by the relevant RATstandard. Other configuration parameters may be modified, in addition tothe ones set out below.

Timers for Handover and Reestablishment

The value of a handover failure timer may be increase to allow forlonger handover execution. More specifically, the T304 handover failuretimer may be extended to support longer handover execution because ofthe limited link budget of the UE. The T304 is an LTE timer which beginsat the receipt of an RRC (Radio Resource Control) ConnectionReconfiguration message along with Mobility Control information. TheT304 timer may also start at the receipt of mobility information from anE-UTRA command message, which may include a cell change order. At expiryof the T304 timer, an action may be selectively performed based on thecurrent need. In the case of a Cell Change Order from the E-ETRA orintra E-UTRA handover, the network may initiate the RRC connectionre-establishment procedure. In the case of handover to E-UTRA, thenetwork may perform actions per the source RAT.

The Time to Trigger (TTT) parameter may be extended to save power and tolimit failure of measurement reports (especially in the case ofmobility). The TTT parameter is the length of time (TTT window) betweenwhen a measurement is begun and the actual measurement report isprovided to the cellular network which handover is prevented fromoccurring. Increasing the length of the TTT timer may operate to preventa ping-pong effect between handovers.

The handover preparation time may be defined as the time from ameasurements report to a handover trigger. In some embodiments, thehandover preparation time may be increased to take into account the linkbudget limitations of the UE device.

FIG. 7—Timers for Handover and Reestablishment

FIG. 7 illustrates operation of various timers for handover andreestablishment, according to some embodiments. As shown, a handoverprocess may be ongoing in State 1, and an event entering condition mayoccur as shown.

The TTT period shown in FIG. 7 is longer than that specified in the RATstandard, i.e., the length of the TTT period timer has been extended byone of the preferred configuration parameters requested by the UE. Afterthe TTT period, the UE may send the measurement reports to the eNB.Measurement Events A2, A3, and/or A4 could be used to provide anindication of UE coverage to the network.

As described above, a link budget limited UE may use SINR values insteadof, or supplemental to, RSRP/RSRQ values in determining when handovershould occur. In order to trigger the measurement reports, the UE mayperform a mapping of measured SINR values (or thresholds) to adjustRSRP/RSRQ values that are reported to the cellular network. The latterwill trigger the A2/3/4 measurement reports. The event A3 indicatesthat, as between neighboring cells, one cell is relatively better thanthe rest. At the edge of a cell with a link budget limited device, theevent A3 may be difficult or impossible to establish because allneighboring cells may be out of range due to the link budget constraintsof the device. The event A4 indicates that signal between the UE and aparticular cell exceeds a threshold value. Because of the link budgetgap for these specific devices, the event A4 may be the most suitableevent for handover management. A link budget limited device may thusrequest an A4 configuration from the eNB in the configuration parametersrequested in 606 of FIG. 6.

Radio Link Failure Procedure

In some embodiments, the radio link failure procedure may be relaxed inorder to avoid excessive connection interruptions. The Radio LinkFailure (RLF) procedure is based on the LTE T310 and N310/N311 timers.The N310 timer essentially counts the number of lost packets, and theN311 timer essentially counts the number of successful decodings orreception for the UE to be deemed back in synch with the eNB.

More specifically, the N310 parameter indicates the number of 200 msintervals when the UE is unable to successfully decode the PDCCH(Physical Downlink Control Channel) due to low RSRP detected. In otherwords, the N310 parameter indicates the number of times in which the UEcannot successfully decode 20 consecutive frames in the downlink. TheT310 is a timer used to allow the UE to get back in synchronization withthe eNB. The N311 parameter indicates the number of 100 ms intervalsthat the UE should successfully decode the PDCCH to be back insynchronization with the eNB. That is, the N311 parameter indicates thenumber of times in which the UE must successfully decode 10 consecutiveframes in the downlink in order for the UE to assume the radio link isin synch. If the UE detects N310 consecutive out-of-sync indications, itstarts the T310 timer. If the T310 timer expires, the link has failed.If the UE detects N311 consecutive in-sync indications prior to the T310timer expiring, then the timer is stopped and the link has not failed.

With a link budget limited UE, it is assumed that packets will be lostmore often, and thus in some embodiments the N310 counter thresholdwhich triggers the RLF may be increase or extended. In some embodiments,the N311 counter which stops the RLF procedure may be reduced, thusmaking it easier (or more lenient) for the UE to be considered back insynch with the eNB.

PDCP/RLC/SR/CQI

The link budget limited UE may request to increase the maximum number ofRLC (radio link control) retransmissions for radio bearers, includingboth data radio bearers (DBRs) and signaling radio bearers (SRB), toavoid having a radio link failure (RLF). This may be especiallyimportant for SRBs.

A link budget limited UE device may further indicate that a packetdiscard timer, such as the PDCP discard timer, should be increased inorder to avoid dropping packets. Thus, where packets are maintained in abuffer until a successful retransmission occurs, it may be desirable toincrease the length of time that packets are allowed to stay in thebuffer until they are discarded. This allows packets to remain in thetransmission buffer for a longer period of time, which is desirablesince the number of retransmission attempts has also been increased asmentioned above. Increasing the PDCP discard timer helps to avoidcausing the UE device to restart a communication from the beginning, anevent that is triggered when a dropped package threshold is reached.

Furthermore, the maximum number of attempts a UE undertakes in sending ascheduling request (SR) over PUCCH may be reduced. A UE may issue a SRto request uplink resources for a given slot in a particular cell in thenetwork. For example, a link budget limited UE may only undertake 3 or 4attempts over PUCCH before dropping to RACH because the marginalbenefits of each additional attempt past the first 3 or 4 may notoutweigh the marginal costs of each additional attempt. In other words,due to the link budget constraints of the UE device, if the UE has notsucceeded in requesting uplink resources after 3 or 4 schedulingrequests, then it is unlikely further scheduling requests will produceresults, i.e., will be received by the cellular network.

A link budget limited may further limit the periodicity of channelquality indicator (CQI) reporting to avoid the resources required formore frequent reporting. Because the UE is link budget limited, thechannel quality may in most instances be somewhat constant, and likelysomewhat poor, and thus fewer CQI reports are needed. Instead ofreporting the CQI every 5 milliseconds (ms), for example, a link budgetlimited device may report every second or every 100 ms. Of course, thefrequency of CQI reporting may also vary based on the current degree ofmovement (mobility) of the UE as well.

RACH Attempts

In current cellular networks, the UE is configured with a maximum numberof RACH attempts. However, a UE that is link budget limited (or linkbudget constrained) is relatively more likely to reach the maximumnumber of RACH attempts. Hence, in some embodiments, the maximum numberof RACH attempts with which the UE is configured may be increased inorder to limit the resource-intensive Out of Service (OOS) procedure.The UE may thus request a RACH attempt value that operates to delay theOOS procedure as much as possible. In the worst case, if the UE is tillnot able to successfully perform a RACH to an eNB, it can declare therespective eNB barred internally and may attempt to perform a subsequentRACH procedure with a different eNB.

Thus preferred configuration parameters requested by the link budgetlimited UE may include new RRC thresholds for events A1/A2/A3/A4; a newPDCP discard timer value; new UL max retransmission threshold; CQItransmission frequency, RACH parameters (e.g., numberofRA-Preambles,powerRampingStep, preambleInitialReceivedTargetPower, preambleTransMax,maxHARQ-Msg3Tx, and dedicated PRACH resources); and various timers andconstants (e.g., T300, T301, T310, N310, N311, and N311).

Other examples of configuration parameters requested by a link budgetlimited UE, as discussed above, may include: new C-DRX parameters; aBearer Resource Modification Request requesting a Quality of serviceClass Identifier (QCI) of, e.g., 6, 7, or 8; and certain GBR (guaranteedbit rate) parameters, which may map to a C-DRX configuration, and whichmay be based on whether a foreground or background application isrunning on the UE.

Embodiments of the present disclosure may be realized in any of variousforms. For example some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured toinclude a processor (or a set of processors) and a memory medium, wherethe memory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A method for operating a user equipment (UE),comprising: at the UE: communicating with a base station in a first cellin a cellular network; performing a measurement of signal tointerference noise ratio (SINR) of communications received by the UE inthe first cell; receiving configuration parameters associated with atleast report triggering event A3, wherein the event A3 indicates that ameasurement of a signal between the UE and a particular cell isrelatively better than a measurement signal between the UE and anothercell, wherein the UE is configured to determine the event A3 based onthe measurement of SINR instead of one or more of: reference signalreceived power (RSRP) or reference signal received quality (RSRQ);determining the event A3 has been triggered based on the measurement ofSINR; and based on determining the event A3 has been triggered,reporting at least the SINR to the first cell.
 2. The method of claim 1,wherein the configuration parameters indicate one or more thresholdsassociated with the event A3.
 3. The method of claim 1, furthercomprising: determining event A2 has been triggered based on ameasurement of SINR of the first cell; and based on determining theevent A2 has been triggered, reporting at least the SINR of the firstcell.
 4. The method of claim 3, wherein the UE is configured todetermine the event A2 based on the SINK of the first cell instead ofone or more of: reference signal received power (RSRP) or referencesignal received quality (RSRQ), wherein the configuration parametersindicate one or more thresholds associated with the event A2.
 5. Themethod of claim 1, further comprising: determining event A4 has beentriggered based on a plurality of SINR measurements; and based ondetermining the event A4 has been triggered, reporting at least one SINRof the plurality of SINR measurements.
 6. The method of claim 5, whereinthe UE is configured to determine the event A4 based on the measurementof SINR instead of one or more of: reference signal received power(RSRP) or reference signal received quality (RSRQ), wherein theconfiguration parameters indicate one or more thresholds associated withthe event A4.
 7. The method of claim 1, further comprising: indicatingto the base station that the UE is link budget limited, wherein saidreceiving the configuration to determine the event A3 based on themeasurement of SINR is in response to the indication.
 8. An apparatus,comprising: one or more processors, wherein the one or more processorsare configured to cause a user equipment (UE) to: communicate with abase station in a first cell in a cellular network; perform ameasurement of signal to interference noise ratio (SINR) ofcommunications received by the UE in the first cell; receiveconfiguration parameters associated with at least report triggeringevent A3, wherein the event A3 indicates that a measurement of a signalbetween the UE and a particular cell is relatively better than ameasurement signal between the UE and another cell, wherein the UE isconfigured to determine the event A3 based on the measurement of SINRinstead of one or more of: reference signal received power (RSRP) orreference signal received quality (RSRQ); determine the event A3 hasbeen triggered based on the measurement of SINR; and based ondetermining the event A3 has been triggered, report at least the SINR tothe first cell.
 9. The apparatus of claim 8, wherein the configurationparameters indicate one or more thresholds associated with the event A3.10. The apparatus of claim 8, wherein the one or more processors arefurther configured to: determine event A2 has been triggered based on ameasurement of SINR of the first cell; and based on determining theevent A2 has been triggered, report at least the SINR of the first cell.11. The apparatus of claim 10, wherein the one or more processors areconfigured to determine the event A2 based on the SINR of the first cellinstead of one or more of: reference signal received power (RSRP) orreference signal received quality (RSRQ), wherein the configurationparameters indicate one or more thresholds associated with the event A2.12. The apparatus of claim 8, wherein the one or more processors arefurther configured to: determine event A4 has been triggered based on aplurality of SINR measurements; and based on determining the event A4has been triggered, report at least one SINR of the plurality of SINRmeasurements.
 13. The apparatus of claim 12, wherein the one or moreprocessors are configured to the event A4 based on the measurement ofSINR instead of one or more of: reference signal received power (RSRP)or reference signal received quality (RSRQ), wherein the configurationparameters indicate one or more thresholds associated with the event A4.14. The apparatus of claim 8, wherein the one or more processors arefurther configured to: indicate to the base station that the UE is linkbudget limited, wherein said receiving the configuration to determinethe event A3 based on the measurement of SINR is in response to theindication.
 15. The apparatus of claim 8, wherein the one or moreprocessors are further configured to: indicate to the base station thatthe UE is link budget limited; receive a time to trigger (TTT) for atleast the event A3, wherein the TTT is longer than a value configuredfor non-link budget limited devices.
 16. A user equipment (UE),comprising: at least one antenna; a radio coupled to the at least oneantenna for performing wireless cellular communications; and at leastone processor coupled to the radio, wherein the at least one processoris configured to: communicate with a base station in a first cell in acellular network; perform a measurement of signal to interference noiseratio (SINR) of communications received by the UE in the first cell;receive configuration parameters associated with at least reporttriggering event A3, wherein the event A3 indicates that a measurementof a signal between the UE and a particular cell is relatively betterthan a measurement signal between the UE and another cell, wherein theUE is configured to determine the event A3 based on the measurement ofSINR instead of one or more of: reference signal received power (RSRP)or reference signal received quality (RSRQ); determine the event A3 hasbeen triggered based on the measurement of SINR; and based ondetermining the event A3 has been triggered, report at least the SINR tothe first cell.
 17. The UE of claim 16, wherein the configurationparameters indicate one or more thresholds associated with the event A3.18. The UE of claim 16, wherein the at least one processor is furtherconfigured to: determine event A2 has been triggered based on ameasurement of SINR of the first cell; and based on determining theevent A2 has been triggered, report at least the SINR of the first cell.19. The UE of claim 16, wherein the at least one processor is furtherconfigured to: determine event A4 has been triggered based on aplurality of SINR measurements; and based on determining the event A4has been triggered, report at least one SINR of the plurality of SINRmeasurements.
 20. The UE of claim 16, wherein the at least one processoris further configured to: indicate to the base station that the UE islink budget limited; receive a time to trigger (TTT) for at least theevent A3, wherein the TTT is longer than a value configured for non-linkbudget limited devices.